Overview. Major depressive disorder is characterized by discrete episodes of at least two weeks' duration (although most episodes last considerably longer) involving clear-cut changes in affect, cognition and neurovegetative functions and inter-episode remissions. A diagnosis based on a single episode is possible, although the disorder is a recurrent one in the majority of cases. Careful consideration is given to the delineation of normal sadness and grief from a major depressive episode. Bereavement may induce great suffering, but it does not typically induce an episode of major depressive disorder. When they do occur together, the depressive symptoms and functional impairment tend to be more severe, and the prognosis is worse compared with bereavement that is not accompanied by major depressive disorder. Bereavement-related depression tends to occur in persons with other vulnerabilities to depressive disorders, and recovery may be facilitated by antidepressant treatment (American Psychiatric Association, 2013).
A more chronic form of depression, persistent depressive disorder (dysthymia), can be diagnosed when the mood disturbance continues for at least two years in adults or one year in children. This diagnosis, new in DSM-5, includes both the DSM-IV diagnostic categories of chronic major depression and dysthymia (American Psychiatric Association, 2013).
Many patients with major depression do not initially complain of depressed mood or anehdonia (American Psychiatric Association, 2013). Clinicians need to suspect this diagnosis based on a profile of common presentations and risk factors, taking into account cultural considerations (American Psychiatric Association, 2013).
Common presentations for patients not complaining of major depression or anhedonia include (American Psychiatric Association, 2013):
The close relationship of mind and body results in the presentation of medical illness with major depression in various forms: (American Psychiatric Association, 2013)
- Medical illness may be a biological cause (e.g., thyroid disorder, stroke).
- Medical illness or the patient's perception of his/her clinical condition and health-related quality of life may trigger a psychological reaction to prognosis, pain or disability (e.g., in a patient with cancer).
- Medical illness may exist coincidentally in a patient with primary mood or anxiety disorder.
Non-mood presentations of major depression include fatigue, pain or other somatic complaints, sleep disturbances, sexual dysfunction, multiple medical visits and work or relationship dysfunction. Fatigue is the seventh most common symptom in primary care, and up to 24% of all patients surveyed in primary care clinics indicate that fatigue is a major problem (Kroenke, 1988).
A mood disorder (major depression, persistent depressive disorder or bipolar) may be present in 39% of patients with a presenting complaint of chronic fatigue (fatigue present at least half the time for at least one month) (Manu, 1988).
Major depression may also be associated with medical disorders or the patient's perception of his/her clinical condition. Although thyroid function abnormalities may cause depressive symptoms, screening for thyroid disease in all patients with major depression is not necessary because the prevalence of unidentified thyroid disease in patients with major depression is the same as in the general population (Garrard, 2001; Briggs, 1993).
Irritable bowel syndrome (IBS) is strongly correlated with psychiatric illness. Treatment of the underlying psychiatric disease may provide more than adequate management of IBS (Garakani, 2003).
For women, severe obesity (body mass index greater than 40) has been strongly associated with depression (Onyike, 2003).
Major depression is also seen in elderly patients with comorbid illnesses, such as cerebrovascular accident (CVA), cancer, dementia or disabilities.
Risk factors for major depression include:
- Family or personal history of major depression and/or substance abuse
- Recent loss
- Chronic medical illness
- Stressful life events that include loss (death of a loved one, divorce)
- Traumatic events (example: car accident)
- Major life changes (examples: job change, financial difficulties)
- Domestic abuse or violence
Note: Genomics: There have been a number of genome-wide association studies for major depression. So far there have been no robust, replicable, single nucleotide polymorphisms identified for depression (Major Depressive Disorder Working Group of the Psychiatric GWAS Consortium, 2013).
One previous episode of major depression is associated with a 50% chance of a subsequent episode, two episodes with a 70% chance, and three or more episodes with a 90% chance (NIMH/NIH Consensus Development Conference Statement, 1985).
Most studies indicate that in 40 to 60% of patients, a major life event precedes the first episode of major depression (Post, 1992).
Domestic abuse and violence. In a recent survey, a stronger association was found between depressed symptoms and ever being afraid of a partner compared with depressed symptoms and hazardous drinking in both men and women, even after adjusting for age group, income, employment status, marital status, living alone and education level (Gilchrist, 2010).
No single tool has been identified as the gold standard for screening of domestic violence or abuse. These two questions are commonly used in assessments:
- Does your partner put you down or try to control what you can do?
- In the past year have you ever been hit, pushed, restrained or choked during an argument?
For more information on domestic violence screening, see the ICSI Preventive Services for Adults guideline.
Whenever You Suspect Depression, Screen for it
Validated and reliable tools can help clinicians identify and systematically monitor patients with major depression. Use screening and tracking tools to enhance but not replace the clinical interview.
Either the PHQ-2 or the PHQ-9 can be used to screen for depression. There is stronger evidence supporting the use of the PHQ-9 in patients with chronic disease.
Use the Patient Health Questionnaire (PHQ) two-question tool in routine screening settings (Gilbody, 2007).
Over the past two weeks, have you been bothered by:
- Little interest or pleasure in doing things?
- Feeling down, depressed or hopeless?
PHQ-2 scores can range from 0 to 6, and a cutpoint ≥ 3 suggests clinically significant depression which should prompt either completion of the full PHQ-9 or a clinical interview to assess for MDD (Kroenke, 2010; Gilbody, 2007).
The PHQ-9 has been validated for measuring depression severity (Kroenke, 2001; Spitzer, 1999) and is validated as a tool for both detecting and monitoring depression in primary care settings (Kroenke, 2010; Wittkampf, 2007). It has a sensitivity (false negative) of 0.77 and specificity (false positive) of 0.85 when using the screened item scoring method. Two other tools with good utility in case finding, aiding diagnosis and severity grading are the Structural Clinical Interview DSM-IV Axis-I Disorders (SCID-I) with a sensitivity of 85% and specificity 82% and the Mini International Neuropsychiatric Interview (MINI) with a sensitivity of 78% and specificity of 85% (Pettersson, 2015).
It can be administered telephonically (Pinto-Meza, 2005) and read to the patient. Elderly patients with mild cognitive impairment can reliably fill out the PHQ-9 (Löwe, 2004). A recent study found the PHQ-9 is useful in psychiatric practices, as well. PHQ-9 scores influenced clinical decision-making for 93% of more than 6,000 patient contacts (Duffy, 2008). The PHQ-9 tool can be found on www.phqscreeners.com or Appendix A of this guideline.
Other recognized and validated tools include the Beck Depression Inventory (http://www.beckinstitute.org/beck-inventory-and-scales/), Hamilton Rating Scale for Depression (HAM-D) (http://www.ids-qids.org/) and the Quick Inventory of Depressive Symptomatology Self-Report (QID-SR) (http://www.ids-qids.org/) (Rush, 2003).
Regardless of the screening tool chosen, it is crucial to document that the patient meets the criteria of at least five symptoms for at least two weeks as defined by the DSM-5 criteria for major depression. One of the symptoms must be depressed mood or loss of interest or pleasure.
The primary objective is to use a standardized instrument that will quantify baseline intensity and document future progress, including response and remission rates.
Use of tools with diverse populations. The factor structure of the nine items in the PHQ-9 is comparable when tested with African Americans, Chinese Americans, Latino and non-Hispanic white patient groups (Huang, 2006). Language versions that are validated for use in primary care are Spanish (Wulsin, 2002) and Chinese (Yeung, 2008). A Thai-language version has also been validated; however, the sensitivity is low (53%). This version could therefore be a useful and reasonable tool to help confirm a suspected depression but less so to screen general populations (Lotrakul, 2008). The PHQ-9 has also been validated in Korean-American patients, although a cutoff point of 5 is suggested for elderly Korean-Americans (Han, 2008; Donnelly, 2007).
The tool and many other language versions can be found at http://www.phqscreeners.com. When administering the PHQ-9, be aware of cultural factors and involve an interpreter if needed. As research develops on risk adjustment and stratification using this tool, the work group will report and refine recommendations.
Clinicians should choose the screening method that best fits their personal preference, the patient population served and the practice setting.
See Appendix D, "Special Populations," for more information regarding screening for the following conditions/populations, as applicable: 1) cardiovascular and cerebrovascular disease, 2) diabetes, 3) chronic pain, 4) geriatrics [includes dementia/cognitive impairment], and 5) pregnant and postpartum women.